Prusa i3 - Setting home

Hi all;

Noob questions firstly so please bare with me because i've read posts, read wiki's, read forums and all i find is contradiction and confusion so if anyone can help please!

1. I have currently my RepRap with 3 end stops, one near all next/near to the motor assemblies (XYZ) - i cannot find a straight answer if this is right or not and they shouldnt be at the opposing extreme (apart from the Z-axis one).
1a - I am using Repietier-Host (mac version) - and sometimes!! i get an alert saying Y axis has detected the endstop but often not, i don't think ive ever got the x axis one to show but sometimes it stops when it hits it sometimes i just tries to smash it to bits. I am using Marlin on the board and have been trying inverted, non inverted nothing appears to work every time. I move an axis then depress the switch and nothing happens. I place the switch 'reversed' i.e. on the 2/3 pin and the board will only turn on when the switches are depressed so i know they work. Can sometime tell me why when I press these switches nothing happens?

2. I am trying to set the 'home' postion and failing every time - i can move in XYZ +100 each time - i measure it with a pair of calipers and its the same each time 100mm - i know that it works; i put them all say to +100 (having taken them just off the limit switches at each end as i have the switches near the motors) i presume this is the 'normal' home location rather than at the other extreme - although i seem to find conflict on this too. Anyway regardless before i go to the +100 positions i.e. they are at what i think should be the ZERO position and press set as home the GCode window responds with yes this is correct they all say 0/0/0 i move them all to plus 100 i.e. away from the motors for each and then press go to home location and they all try and destory themselves and smash and ignore the limit switches. I am certain that they are moving the correct distance when i do it manually but i cannot get home to respond. Does anyone know how i set up the home location or have i got something really backwards? Should it all be other way around i.e. Y & X should be at the extreme then +'ve motion is towards the motors and end stop? And the Z should be zero at the bottom but the home should be +200mm?

Sorry for such a basic question but I am going around in circles and i dont have anyone to ask.

Cheer hopefully someone can give me some pointers.

R

Your end stops should probably be set at the MIN position on all axis. If they are next to your motors, than this sounds like you are at the correct positions.

1) Check your hardware. The GCode command M119 is very helpful. It will tell you the current status of all endstops. You can MANUALLY trigger an endstop, send M119, and see that it is reported as pressed. If you do not get the correct results, something is wrong with your wiring. If your wiring is wrong, nothing else will make sense. Check each switch first this way and you can be confident your switches are functional.

2) There are many settings in your Configuration.h file (assuming you are using the Marlin firmware) that apply to endstops. Many of these govern the behavior you are seeing.

For example:
#define min_software_endstops false // If true, axis won't move to coordinates less than HOME_POS.
#define max_software_endstops true // If true, axis won't move to coordinates greater than the defined lengths below.

Define whether or not you can move your device past the minimum and maximum positions allowed by the endstops.

There is an entire section labeled thus:
//===========================================================================
//=============================Mechanical Settings===========================
//===========================================================================

That provides many settings for endstops. This is the place to start to understand what is happening, assuming everything is wired up correctly.

Good luck,
-Matt